1. Field of the Invention
The invention relates to semiconductor devices and components and, specifically, to metal oxide dielectric materials for use in semiconductor devices and components.
2. Description of Related Art
Silicon dioxide (SiO2) is widely employed in the semiconductor industry as a gate dielectric for both logic and memory applications. When SiO2, which has a dielectric constant (K) value of approximately 4, is employed in a thin (i.e., less than about 15 Å) layer, the amount of leakage current from the gate dielectric can become prohibitively high.
To reduce leakage current, SiO2 has been substituted with a high K dielectric material, i.e., a material with a K value of greater than 4. Most of these high K gate dielectrics are metal oxides. For example, U.S. Pat. No. 6,184,072 describes using metals like zirconium and hafnium to increase the dielectric value of an SiO2 gate dielectric layer. Most metal oxides, however, have a large number of structural defects. Problems associated with the use of metal oxides having these structural defects include high interface state densities between the oxide and the underlying semiconductor. These charges can provide a conduction path in the dielectric layer, which leads to adverse device performance. That is, these defects may generate a conduction path in the dielectric, and may also generate charges in the dielectric and at the dielectric/Si interface. The presence of these charges (fixed charges) in the dielectric affects the threshold voltage of a transistor having a metal oxide gate dielectric, and more importantly, the carrier mobility at the dielectric/Si interface.